Stirling cooler

ABSTRACT

Disclosed is a stirling cooler, in which a cylinder is fixedly installed in a case, a flange is protruded perpendicularly from an outer surface of the cylinder in a radial direction of the cylinder, a stair on which the flange is seated is installed in the case in an axial direction of the cylinder, and a packing is interposed between the stair of the case and the flange of the cylinder, thereby preventing the packing from influencing an axis of the cylinder and thus maintaining the sealed state between the case and the cylinder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stirling cooler, and moreparticularly to a stirling cooler, in which a packing for maintaining ahermetically sealed state is positioned at a portion connecting acylinder and a case in an axial direction of the cylinder.

2. Description of the Related Art

As shown in FIG. 1, a conventional stirling cooler comprises a case 4provided with a cold tip 2 at an opened end thereof, a cylinder 6fixedly installed in the case 4 and filled with a fluid, a piston 8installed in the cylinder 6 such that the piston 8 can reciprocate, andprovided with a hollow 7 formed therein, a displacer 10 installed in thehollow 7 of the piston 8 such that the displacer 10 can reciprocate, aregenerator 12 longitudinally connected to the displacer 10, andprovided with a cavity 1 positioned between the regenerator 12 and thecold tip 2 and filled with the fluid, and a heat exchanger 14 connectedto the cylinder 6 and the regenerator 12.

A flange 5 is vertically formed along an outer surface of the cylinder 6in a radial direction, and a protrusion 3, on which the flange 5 isseated in an axial direction of the cylinder 6, is formed on the case 4.The flange 5 of the cylinder 6 is connected to the protrusion 3 of thecase 4 by screws 16.

The piston 8 is connected to a linear motor 18 installed between thecase 4 and the cylinder 6, and reciprocates. The displacer 10 isconnected to an elastic member 19 installed in the case 2 such that thedisplacer 10 is opposite to the regenerator 12, thus being elasticallysupported such that the displacer 10 faces the cold tip 2. A hole 11 isformed in a lower part of the regenerator 12 being opposite to the coldtip 2.

The heat exchanger 14 includes an inner heat exchanger 13 installed in aheat exchange chamber 20 prepared between the cylinder 6 and the case 4,and an outer heat exchanger 15 installed on an outer surface of the case4 so that the case 4 is interposed between the inner heat exchanger 13and the outer heat exchanger 15. A first hole 22 communicating with theheat exchanger chamber 20 is formed through the cylinder 6, and a secondhole 24 communicating with a hole 9 formed through the displacer 10positioned at the heat exchange chamber 20 and the regenerator 12.

An O-ring 30 is positioned at a contact portion of the outer surface ofthe cylinder 6 and the case 4 in a radial direction of the cylinder 6 sothat the fluid does not leak from the heat exchange chamber 20.

Hereinafter, operation of the above-described conventional stirlingcooler will be described in detail.

When the piston 8 moves close to the cold tip 2, the fluid of thecylinder 6 is isothermally compressed, and is discharged to the heatexchange chamber 20 to emit heat. Then, the fluid is introduced into theregenerator 12 to emit sensible heat, and fills the cavity 1 between theregenerator 12 and the cold tip 2 and is isothermally expandedsimultaneously. Here, as the fluid fills the cavity 1 between theregenerator 12 and the cold tip 2, the regenerator 12 and the displacer10 move away from the cold tip 2.

Thereafter, when the piston 8 moves away from the cold tip 2, thedisplacer 10 and the regenerator 12 are returned to their earlierpositions toward the cold tip 2 by the elastic force of the elasticmember 18. The fluid filling the cavity 1 between the regenerator 12 andthe cold tip 2 subsequently passes through the regenerator 12 and theheat exchange chamber 20 to absorb heat, and re-fills the cylinder 6.

Since the cylinder 6 provided with the O-ring 30 is inserted into thecase 4 in the conventional stirling cooler, the O-ring 30 between thecase 4 and the cylinder 6 is overloaded, thus being damaged and causingchange in an axis of the cylinder 6. Thereby, the displacer 10 and thepiston 8 reciprocating in the cylinder 6 are easily worn out, thuscausing errors in operating the stirling cooler.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the aboveproblems, and it is an object of the present invention to provide astirling cooler, in which a packing prevents a fluid from leaking anddoes not influence an axis of a cylinder when the cylinder is assembledin a case.

In accordance with one aspect of the present invention, the above andother objects can be accomplished by the provision of a stirling coolercomprising: a case provided with a cold tip at an end thereof; acylinder fixedly installed in the case and provided with a pistonreciprocating therein; a displacer installed in the piston such that thedisplacer can reciprocate; a regenerator positioned between thedisplacer and the cold tip; a heat exchanger connected to theregenerator and the cylinder; and a packing positioned at an area, inwhich the cylinder contacts the case, in an axial direction of thecylinder.

Preferably, the heat exchanger may include an inner heat exchangerinstalled in a heat exchange chamber positioned between the cylinder andthe case, and an outer heat exchanger installed on an outer surface ofthe case opposite to the inner heat exchanger; and the packing may bepositioned at the heat exchange chamber for maintaining the sealed stateof the heat exchanger chamber.

Further, preferably, an O-ring may be installed at an outer surface ofthe cylinder opposite to the inner heat exchanger.

Moreover, preferably, an O-ring may be installed at a portion of thecylinder contacting the case in a radial direction of the cylinder fordefining the heat exchange chamber, and the O-ring and the packing maybe respectively positioned at opposite sides of the heat exchangechamber in the axial direction of the cylinder.

Preferably, the packing may be interposed between a flange protrudedperpendicularly from an outer surface of the cylinder and a stair of thecase on which the flange is seated.

Further, preferably, through holes for connecting the flange of thecylinder and the stair of the case by screws may be formed through thepacking.

Moreover, preferably, the packing may have a ring shape so that it isinserted into the outer surface of the cylinder.

In accordance with another aspect of the present invention, there isprovided a stirling cooler comprising: a case provided with a cold tipat an end thereof; a cylinder fixedly installed in the case and providedwith a piston reciprocating therein; a displacer installed in the pistonsuch that the displacer can reciprocate; a regenerator positionedbetween the displacer and the cold tip; a heat exchanger including innerand outer units respectively installed at the inside and outside of aheat exchange chamber positioned between the cylinder and the case andconnected to the regenerator and the cylinder; and a packing interposedbetween a flange protruded perpendicularly from an outer surface of thecylinder and a stair of the case on which the flange is seated in anaxial direction of the cylinder for maintaining the sealed state of theheat exchange chamber.

In accordance with yet another aspect of the present invention, there isprovided a stirling cooler comprising: a case provided with a cold tipat an end thereof; a cylinder fixedly installed in the case and providedwith a piston reciprocating therein; a displacer installed in the pistonsuch that the displacer can reciprocate; a regenerator positionedbetween the displacer and the cold tip; a heat exchanger including innerand outer units respectively installed at the inside and outside of aheat exchange chamber positioned between the cylinder and the case andconnected to the regenerator and the cylinder; a packing interposedbetween a flange protruded perpendicularly from an outer surface of thecylinder and a stair of the case on which the flange is seated in anaxial direction of the cylinder for maintaining the sealed state of theheat exchange chamber; and an O-ring positioned at an outercircumference of a portion of the cylinder defining the heat exchangechamber such that the O-ring is separated from the packing in an axialdirection of the cylinder and contacts the case in a radial direction ofthe cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a longitudinal-sectional view of a conventional stirlingcooler;

FIG. 2 is a longitudinal-sectional view of a stirling cooler inaccordance with the present invention; and

FIG. 3 is a plan view of a packing of the stirling cooler in accordancewith the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, a preferred embodiment of the present invention will be describedin detail with reference to the annexed drawings.

The present invention may comprise several embodiments, but the mostpreferred embodiment will be described hereinafter. In the followingdescription of the present invention, a detailed description of knownfunctions and configurations incorporated herein will be omitted when itmay make the subject matter of the present invention rather unclear.

As shown in FIG. 2, a stirling cooler in accordance with the presentinvention comprises a case 50 provided with a cold tip 52 at an openedend thereof, a cylinder 54 fixedly installed in the case 50 and filledwith a fluid, and a packing 70 positioned at a contact area between thecase 50 and the cylinder 54 in an axial direction of the cylinder 54.

A linear motor 56 is installed between the case 50 and an upper part ofthe cylinder 54, a piston 58 connected to the linear motor 56 isinstalled in the cylinder 54 such that the piston 58 can reciprocate, adisplacer 62 supported by an elastic member 60 installed on the case 50is installed in the piston 58 such that the displacer 62 canreciprocate, and a regenerator 64 is installed between the displacer 62and the cold tip 52.

A heat exchange chamber 66 is installed in the case 50 and the lowerpart of the cylinder 52, and communicates with the cylinder 52 and theregenerator 64 such that the heat exchange chamber 66 exchanges heat ofthe fluid with the cylinder 52 and the regenerator 64. An inner heatexchanger 68 is installed in the heat exchange chamber 66, and an outerheat exchanger 69 surrounding the heat exchange chamber 66 is installedon an outer surface of the case 50 so that the case 50 is interposedbetween the inner heat exchanger 68 and the outer heat exchanger 69.

Here, the heat exchange chamber 66 is configured such that two contactportions 53 and 53′ of the cylinder 54, which are separated from eachother in the axial direction of the cylinder 54, contact the case 50,and the lower contact portion 53′ of the cylinder 54 has a widthnarrower than that of the upper contact portion 53 of the cylinder 54.Further, the case 50 has a stepwise structure including two stairs 51and 51′ so that the upper stair 51 of the case 50 contacts the uppercontact portion 53 of the cylinder 54 and the lower stair 51′ of thecase 50 contacts the lower contact portion 53′ of the cylinder 54,thereby being provided with the heat exchange chamber 66.

The fluid flows in the heat exchange chamber 66 between the cylinder 54and the regenerator 64, and requires the packing 70 for maintaining ahermetically sealed state of the heat exchange chamber 66, inserting thecylinder 54 into a gap between the stairs 51 and 51′ of the case 50 andpreventing the change in an axis of the cylinder 54.

Since the upper stair 51 of the case 50 more influences the axis of thecylinder 54, the packing 70 is positioned at the upper stair 51 of thecase 50.

Accordingly, a flange 55 is protruded perpendicularly from the outersurface of the cylinder 54 in a radial direction, and seated on theupper stair 51 of the case 50 in the axial direction of the cylinder 54,and the packing 70 is interposed between the upper stair 51 of the case50 and the flange 55 of the cylinder 54.

The above packing 70 has a ring shape so that it is inserted into thewhole outer circumference of the cylinder 54 for hermetically sealingthe heat exchange chamber 66. Further, a radius of the packing 70, i.e.,a distance from a center of the packing 70 to the outer circumference ofthe packing 70, is approximately the same as a distance from the centerof the cylinder 54 to the flange 55 of the cylinder 54 in the radialdirection of the cylinder 54. Here, in order to uniformly compress thering-shaped packing 70 in the radial direction of the cylinder 54 andfirmly sealing the heat exchange chamber 66, the flange 55 of thecylinder 54 has a ring shape. Therefore, the packing 70 and the flange55 of the cylinder 54 have the same shape.

Since the upper stair 51 of the case 50 and the flange 55 of thecylinder 54 are connected to each other by screws 80, the packing 70includes through holes 71, into which the screws 80 are inserted, sothat the packing 70 together with the cylinder 54 is fixed to the case50.

An O-ring 72 for firmly maintaining the sealed state of the heatexchange chamber 66 is positioned at the lower contact portion 53′ ofthe cylinder 54. The O-ring 72 and the packing 70 are opposite to theheat exchange chamber 66 in the axial direction of the cylinder 54, thusmaintaining the sealed state of the heat exchange chamber 66.

Further, an O-ring 74 for maintaining the sealed state of the inner heatexchanger 68 is positioned at the outer surface of the cylinder 54located at the height of the heat exchange chamber 66.

Hereinafter, operation and effects of the cryogenic regenerator inaccordance with the present invention will be described in detail.

When the linear motor 56 is operated, the piston 58 moves close to thecold tip 52 and the fluid of the cylinder 54 passes through the heatexchange chamber 66 and the regenerator 64 and flows between theregenerator 64 and the cold tip 52. Then, the regenerator 64 and thedisplacer 62 move away from the cold tip 52.

On the other hand, when the piston 58 moves away from the cold tip 52 bymeans of the operation of the linear motor 56, the fluid filling a gapbetween the regenerator 64 and the cold tip 52 flows into theregenerator 64 and the heat exchange chamber 66 and re-fills thecylinder 54.

Here, since the heat exchange chamber 66 is firmly sealed by the packing70 and the O-rings 72 and 74, the fluid filling the heat exchangechamber 66 cannot leak into spaces other than the regenerator 64.

Since the packing 70 between the upper stair 51 of the case 50 and theflange 55 of the cylinder 54 is compressed in the axial direction of thecylinder 54, the cylinder 54 is easily assembled in the case 50.Further, the piston 58 and the displacer 62 reciprocate in the axialdirection of the cylinder 54, thus improving the life span of thecylinder 54, the piston 58 and the displacer 62.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A stirling cooler comprising: a case provided with a cold tip at anend thereof; a cylinder fixedly installed in the case and provided witha piston reciprocating therein; a displacer installed in the piston suchthat the displacer can reciprocate; a regenerator positioned between thedisplacer and the cold tip; a heat exchanger connected to theregenerator and the cylinder; and a packing positioned at an area, inwhich the cylinder contacts the case, in an axial direction of thecylinder.
 2. The stirling cooler as set forth in claim 1, wherein: theheat exchanger includes an inner heat exchanger installed in a heatexchange chamber positioned between the cylinder and the case, and anouter heat exchanger installed on an outer surface of the case oppositeto the inner heat exchanger; and the packing is positioned at the heatexchange chamber for maintaining the sealed state of the heat exchangerchamber.
 3. The stirling cooler as set forth in claim 2, wherein anO-ring is installed at an outer surface of the cylinder opposite to theinner heat exchanger.
 4. The stirling cooler as set forth in claim 2,wherein an O-ring is installed at a portion of the cylinder contactingthe case in a radial direction of the cylinder for defining the heatexchange chamber.
 5. The stirling cooler as set forth in claim 4,wherein the O-ring and the packing are respectively positioned atopposite sides of the heat exchange chamber in the axial direction ofthe cylinder.
 6. The stirling cooler as set forth in claim 1, whereinthe packing is interposed between a flange protruded perpendicularlyfrom an outer surface of the cylinder and a stair of the case on whichthe flange is seated.
 7. The stirling cooler as set forth in claim 6,wherein the flange of the cylinder has a ring shape.
 8. The stirlingcooler as set forth in claim 6, wherein through holes for connecting theflange of the cylinder and the stair of the case by screws are formedthrough the packing.
 9. The stirling cooler as set forth in claim 6,wherein the packing has a ring shape so that it is inserted into theouter surface of the cylinder.
 10. The stirling cooler as set forth inclaim 6, wherein the packing has a radius, defining a distance from thecenter thereof to the outer circumference thereof, being the same as adistance from the center of the cylinder to the flange of the cylinderin a radial direction of the cylinder.
 11. A stirling cooler comprising:a case provided with a cold tip at an end thereof; a cylinder fixedlyinstalled in the case and provided with a piston reciprocating therein;a displacer installed in the piston such that the displacer canreciprocate; a regenerator positioned between the displacer and the coldtip; a heat exchanger including inner and outer units respectivelyinstalled at the inside and outside of a heat exchange chamberpositioned between the cylinder and the case and connected to theregenerator and the cylinder; and a packing interposed between a flangeprotruded perpendicularly from an outer surface of the cylinder and astair of the case on which the flange is seated in an axial direction ofthe cylinder for maintaining the sealed state of the heat exchangechamber.
 12. The stirling cooler as set forth in claim 11, whereinthrough holes for connecting the flange of the cylinder and the stair ofthe case by screws are formed through the packing.
 13. The stirlingcooler as set forth in claim 11, wherein the packing has a ring shape sothat it is inserted into the outer surface of the cylinder.
 14. Thestirling cooler as set forth in claim 11, wherein an O-ring is installedat an outer surface of the cylinder opposite to the inner heatexchanger.
 15. The stirling cooler as set forth in claim 11, wherein anO-ring is installed at a portion of the cylinder contacting the case ina radial direction of the cylinder for defining the heat exchangechamber.
 16. The stirling cooler as set forth in claim 15, wherein theO-ring and the packing are respectively positioned at opposite sides ofthe heat exchange chamber in the axial direction of the cylinder.
 17. Astirling cooler comprising: a case provided with a cold tip at an endthereof; a cylinder fixedly installed in the case and provided with apiston reciprocating therein; a displacer installed in the piston suchthat the displacer can reciprocate; a regenerator positioned between thedisplacer and the cold tip; a heat exchanger including inner and outerunits respectively installed at the inside and outside of a heatexchange chamber positioned between the cylinder and the case andconnected to the regenerator and the cylinder; a packing interposedbetween a flange protruded perpendicularly from an outer surface of thecylinder and a stair of the case on which the flange is seated in anaxial direction of the cylinder for maintaining the sealed state of theheat exchange chamber; and an O-ring positioned at an outercircumference of a portion of the cylinder defining the heat exchangechamber such that the O-ring is separated from the packing in an axialdirection of the cylinder and contacts the case in a radial direction ofthe cylinder.
 18. The stirling cooler as set forth in claim 17, whereinthrough holes for connecting the flange of the cylinder and the stair ofthe case by screws are formed through the packing.
 19. The stirlingcooler as set forth in claim 17, wherein the packing has a ring shape sothat it is inserted into the outer surface of the cylinder.
 20. Thestirling cooler as set forth in claim 17, wherein an O-ring is installedat an outer surface of the cylinder opposite to the inner heatexchanger.